Besides adding hwseq this patch also introduces these unrelated changes:

Fix enable_flash_ich_dc_spi to pass ERROR_FATAL from ich_init_spi.
The whole error handling looks a bit odd to me, so this patch does
change very little. Also, it does not touch the tunnelcreek method,
which should be refactored anyway.

Add null-pointer guards to find_opcode and find_preop
to matches the other opcode methods better:
curopcodes == NULL has some meaning and is actively used/checked in
other functions.